U.S. patent number 4,259,478 [Application Number 06/103,805] was granted by the patent office on 1981-03-31 for process for preparing high molecular weight copolyesters.
This patent grant is currently assigned to Eastman Kodak Company. Invention is credited to Winston J. Jackson, Jr., Herbert F. Kuhfuss.
United States Patent |
4,259,478 |
Jackson, Jr. , et
al. |
March 31, 1981 |
Process for preparing high molecular weight copolyesters
Abstract
Disclosed is a process for preparing linear, high molecular
weight copolyesters from either (A) polyesters or copolyesters, the
acid component of which consists of at least 70 mole percent
terephthalic acid and the diol component of which consists of at
least 70 mole percent ethylene glycol or (B) copolyesters, the acid
component of which consists of at least 70 mole percent
terephthalic acid and the diol component of which consists of at
least 70 mole percent of a mixture of ethylene glycol and
1,4-cyclohexanedimethanol in a mole ratio of from 20:80 to 97:3,
the process comprising heating the polymer in the presence of
1,4-cyclohexanedimethanol to glycolize the polymer, distilling out
ethylene glycol from the glycolysis mixture, and polycondensing the
glycolysis mixture to form a copolyester of which at least a
portion of ethylene glycol units are replaced by
1,4-cyclohexanedimethanol units. The process provides a fast
polymerization rate and the polymers so produced can be used in the
manufacture of plastics, fibers, films and other shaped objects
having good physical properties.
Inventors: |
Jackson, Jr.; Winston J.
(Kingsport, TN), Kuhfuss; Herbert F. (Kingsport, TN) |
Assignee: |
Eastman Kodak Company
(Rochester, NY)
|
Family
ID: |
22297121 |
Appl.
No.: |
06/103,805 |
Filed: |
December 14, 1979 |
Current U.S.
Class: |
528/307;
521/48.5; 525/437; 525/444; 528/272 |
Current CPC
Class: |
C08G
63/78 (20130101) |
Current International
Class: |
C08G
63/00 (20060101); C08G 63/78 (20060101); C08G
063/18 () |
Field of
Search: |
;528/272,307,309
;260/2.3 ;525/437,444 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Phynes; Lucille M.
Attorney, Agent or Firm: Stevens; John F. Reece III; Daniel
B.
Claims
We claim:
1. Process for preparing linear, high molecular weight copolyesters
from polymers selected from the group consisting of (A) polyesters
or copolyesters, the acid component of which consists of at least
70 mole percent terephthalic acid and the diol component of which
consists of at least 70 mole percent ethylene glycol and (B)
copolyesters, the acid component of which consists of at least 70
mole percent terephthalic acid and the diol component of which
consists of at least 70 mole percent of a mixture of ethylene
glycol and 1,4-cyclohexanedimethanol in a mole ratio of from 20:80
to 97:3, said process comprising
(a) heating said polymer to a temperature of from about 200.degree.
C. to about 290.degree. C. in the presence of about 3 mole percent
to an amount equivalent to the mole percent of ethylene glycol of
1,4-cyclohexanedimethanol to thereby glycolize said polymer,
(b) distilling out at least a portion of the ethylene glycol from
the glycolysis mixture, and
(c) polycondensing the glycolysis mixture to form a copolyester of
which at least a portion of ethylene glycol units are replaced by
1,4-cyclohexanedimethanol units and the inherent viscosity is at
least 0.4.
2. Process according to claim 1 wherein said polymer has an
inherent viscosity of at least 0.6.
3. Process according to claim 2 wherein said polymer has an
inherent viscosity of from about 0.4 to about 0.7.
4. Process according to claim 1 wherein said polymer is heated to a
temperature of about 275.degree. C. in step (b) and maintained at
such temperature for a time of at least 5 minutes.
5. Process for preparing linear, high molecular weight copolyesters
from polyesters or copolyesters, the acid component of which
consists of at least 70 mole percent terephthalic acid and the diol
component of which consists of at least 70 mole percent ethylene
glycol which comprises
(a) heating said polymer to a temperature of from about 200.degree.
C. to about 290.degree. C. in the presence of about 3 mole percent
to an amount equivalent to the mole percent of ethylene glycol of
1,4-cyclohexanedimethanol to thereby glycolize said polymer,
(b) distilling out at least a portion of the ethylene glycol from
the glycolysis mixture, and
(c) polycondensing the glycolysis mixture to form a copolyester of
which at least a portion of ethylene glycol units are replaced by
1,4-cyclohexanedimethanol units and the inherent viscosity is at
least 0.4.
6. Process according to claim 5 wherein the acid component of said
polyester or copolyester comprises from about 70 to about 99.5 mole
percent terephthalic acid and from about 30 to about 0.5 mole
percent of an aliphatic, alicyclic or aromatic dicarboxylic acid
other than terephthalic.
7. Process according to claim 5 wherein the diol component of said
polyester or copolyester comprises from about 70 to about 99.5 mole
percent of ethylene glycol and from about 30 to about 0.5 mole
percent of another aliphatic glycol having from 2 to 8 carbon
atoms.
8. Process for preparing linear, high molecular weight copolyesters
from copolyesters, the acid component of which consists of at least
70 mole percent terephthalic acid and the diol component of which
consists of at least 70 mole percent of a mixture of ethylene
glycol and 1,4-cyclohexanedimethanol in a mole ratio of from 20:80
to 97:3, said process comprising
(a) heating said polymer to a temperature of from about 200.degree.
C. to about 290.degree. C. in the presence of about 3 mole percent
to an amount equivalent to the mole percent of ethylene glycol of
1,4-cyclohexanedimethanol to thereby glycolize said polymer,
(b) distilling out at least a portion of the ethylene glycol from
the glycolysis mixture, and
(c) polycondensing the glycolysis mixture to form a copolyester of
which at least a portion of ethylene glycol units are replaced by
1,4-cyclohexanedimethanol units and the inherent viscosity is at
least 0.4.
9. Process according to claim 8 wherein the acid component of said
polyester or copolyester comprises from about 70 to about 99.5 mole
percent terephthalic acid and from about 30 to about 0.5 mole
percent of an aliphatic, alicyclic or aromatic dicarboxylic acid
other than terephthalic.
10. Process according to claim 8 wherein the diol component of said
polyester or copolyester comprises from about 70 to about 99.5 mole
percent of a mixture of ethylene glycol and
1,4-cyclohexanedimethanol in a mole ratio of from 20:80 to 97:3 and
from about 30 to about 0.5 mole percent of another aliphatic glycol
having from 2 to 8 carbon atoms.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for utilizing polyethylene
terephthalate, especially scrap polyethylene terephthalate in the
production of linear, high molecular weight copolyesters.
The growing demand for polyethylene terephthalate disposable
containers such as beverage bottles has created a need to develop
uses for scrap polyethylene terephthalate. The present invention
provides a process for utilizing polyethylene terephthalate as a
reactive intermediate in the production of copolyesters useful in
the manufacture of such products as fibers, films, and other shaped
objects.
2. Description of the Prior Art
Numerous patents disclose processes for utilizing scrap polyesters
in polymer production such as U.S. Pat. Nos. 3,222,999, 3,344,091,
4,078,143 and 4,138,374.
In U.S. Pat. No. 3,222,299 it is stated that reclaimed monomer,
obtained by heating waste polymer with glycol, may be injected into
the polymerization system but must be kept below a level of about
20% of the total monomer if the polymer produced is to have
satisfactory properties. When amounts of recovered monomer higher
than about 20% are injected, it is found that the rate of
polymerization of the mixture is reduced to such an extent that the
output of the equipment must be cut back to a prohibitively low
level. In the present process, 100% scrap polyester can be utilized
with no loss in properties or polymerization rate. In fact, the
polymerization rate is faster than the rate for the preparation of
the same copolyesters from dimethyl terephthalate, ethylene glycol,
and 1,4-cyclohexanedimethanol.
SUMMARY OF THE INVENTION
The present invention provides a process for preparing linear, high
molecular weight copolyesters from either (A) polyesters or
copolyesters, the acid component of which consists of at least 70
mole percent terephthalic acid and the diol component of which
consists of at least 70 mole percent ethylene glycol or (B)
copolyesters, the acid component of which consists of at least 70
mole percent terephthalic acid and the diol component of which
consists of at least 70 mole percent of a mixture of ethylene
glycol and 1,4-cyclohexanedimethanol in a ratio of from 20:80 to
97:3, the process comprising
(1) heating the polymer to a temperature of from about 200.degree.
C. to about 290.degree. C. in the presence of about 3 mole percent
to an amount equivalent to the mole percent of ethylene glycol of
1,4-cyclohexanedimethanol to glycolize the polymer,
(2) distilling out at least a portion of the ethylene glycol from
the glycolysis mixture, and
(3) polycondensing the glycolysis mixture to form a copolyester of
which at least a portion of ethylene glycol units are replaced by
1,4-cyclohexanedimethanol units and the inherent viscosity is at
least 0.4.
The process provides a fast polymerization rate and the polymers so
produced can be used in the manufacture of plastics, fibers, films
and other shaped objects having good physical properties.
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention, a process is provided for
preparing linear, high molecular weight copolyesters from
either.
(A) polyesters or copolyesters, the acid component of which
consists of at least 70 mole percent terephthalic acid and the diol
component of which consists of at least 70 mole percent ethylene
glycol, or
(B) copolyesters, the acid component of which consists of at least
70 mole percent terephthalic acid and the diol component of which
consists of at least 70 mole percent of a mixture of ethylene
glycol and 1,4-cyclohexanedimethanol in a ratio of from 20:80 to
97:3.
In the first step of the process, the polymer is heated to a
temperature of from about 200.degree. C. to about 290.degree. C.,
in the presence of from about 3 mole percent up to an amount
equivalent to the mole percent of ethylene glycol in the polymer,
of 1,4-cyclohexanedimethanol to glycolize the polymer. Next, at
least a portion of the ethylene glycol is removed from the
glycolysis mixture by distillation. Normally, the mixture is heated
to a temperature of about 275.degree. C. for about 30 to 60 minutes
to accomplish this distillation. In a subsequent step, the
glycolysis mixture is polycondensed to form a copolyester of which
at least a portion of the ethylene glycol units are replaced by
1,4-cyclohexanedimethanol units and the inherent viscosity has
reached at least 0.4.
Polyethylene terephthalate and/or polyethylene
terephthalate/cyclohexanedimethanol copolyesters with an I.V. of at
least 0.2 can be used to prepare the copolyesters of this
invention. Preferably, scrap polyethylene terephthalate with an
I.V. of 0.3-0.6 is used. The acid portion of the polyethylene
terephthalate or polyethylene terephthalate/cyclohexanedimethanol
copolyester used in this invention may be modified with up to 30
mole % of other aliphatic, alicyclic or aromatic dicarboxylic acids
such as isophthalic acid, 2,6-naphthalenedicarboxylic acid, cis or
trans-1,4-cyclohexanedicarboxylic acid, monochloroterephthalic
acid, dichloroterephthalic acid, methylterephthalic acid,
dimethylterephthalic acid, 4,4'-diphenyldicarboxylic acid, adipic
acid, azelaic acid, and dodecanedicarboxylic acid. No. additional
modifier is preferred.
The diol portion of the polyethylene terephthalate or polyethylene
terephthalate/cyclohexanedimethanol copolyester used in this
invention may be modified with up to 30 mole % of an aliphatic
glycol such as 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, or
2,2-dimethyl-1,3-propanediol. No additional modifier is
preferred.
The copolymers of this invention are made by glycolysis of
polyethylene terephthalate of polyethylene
terephthalate/cyclohexanedimethanol copolyesters (preferably scrap
polyester) with 1,4-cyclohexanedimethanol at about 275.degree. C.
The glycolysis can also be carried out on mixtures of polyethylene
terephthalate and copolyesters of polyethylene terephthalate
modified with about 3 to 80 mole % 1,4-cyclohexanedimethanol. A
glycolysis temperature lower than 275.degree. C. can be used, but
the temperature must be above the melting point of the polyester so
the polyester will be molten. Glycolysis temperatures as low as
200.degree. C. can be used with the lower melting copolyesters
under these conditions, or as high as about 290.degree. C., but a
temperature of about 275.degree. C. is preferred. The glycolysis
step is completed in the laboratory in about 5 min. if the
glycolysis temperature is about 275.degree. C. Longer times are
required at lower temperatures. A vacuum of about 0.5 millimeter is
then applied, and stirring is continued until a high-melt viscosity
polymer is obtained. During this polycondensation step, ethylene
glycol is eliminated. If the copolymer has a high enough
crystalline melting point (at least about 200.degree. C.), its
molecular weight may be increased by heating particles of the
polymer in an inert atmosphere or under reduced pressure at a
temperature just below the softening point of the polymer by
conventional solid-phase polymerization.
Using the melt process polyethylene terephthalate may be modified
with 3 to 95 mole % 1,4-cyclohexanedimethanol and polyethylene
terephthalate/cyclohexanedimethanol polyesters may be modified with
up to 95 mole % 1,4-cyclohexanedimethanol. Since
1,4-cyclohexanedimethanol has a boiling point of about 285.degree.
C. and essentially none is lost during the polymerization, the
theoretical amount of 1,4-cyclohexanedimethanol can be used in the
preparation of the copolymers. The 1,4-cyclohexanedimethanol may be
the cis or trans isomer, but the commercially available 30/70
cis/trans isomer mixture is preferred. Since a very short time is
required to carry out glycolysis of the polyesters of this
invention by the 1,4-cyclohexanedimethanol, the time needed to
prepare the copolymers of this invention is considerably less than
the time required to prepare the same copolymers by the
conventional procedure, using dimethyl terephthalate, ethylene
glycol, and 1,4-cyclohexanedimethanol.
The inherent viscosity of the copolyesters of this invention is at
least 0.4 and preferably at least 0.6.
Tough films are obtained by pressing or by extrusion. Molding
plastics having good properties are obtained by injection molding
at about 240.degree.-300.degree. C., depending on the melting point
of the copolyester. In addition to plastics, the compositions of
this invention may be fabricated to give other types of shaped
objects, such as foamed plastics, fibers, films, extruded shapes,
and coatings. The compositions of this invention also may contain
nucleating agents, fibers, pigments, glass fibers, asbestos fibers,
antioxidants, plasticizers, lubricants, and other additives.
The following examples are submitted for a better understanding of
the invention. All inherent viscosities are determined at
25.degree. C. in a (60/40 by weight) mixture of
phenol/tetrachloroethane at a concentration of 0.5 g/100 ml. The
melting points and glass transition temperatures are determined
with a Perkin-Elmer DSC-2 differential scanning calorimeter.
The 1,4-cyclohexanedimethanol used for glycolysis of the polyesters
may be the cis or trans isomer, but the commercially available
30/70 cis/trans isomer ratio is used in the examples below.
The compositions are dried in an oven at 60.degree. C. overnight
and injection molded to give 21/2.times.3/8.times.1/16-in. tensile
bars and 5.times.1/2.times.1/8-ins. flexure bars for testing. ASTM
procedures are used for measuring the tensile strength and
elongation (ASTM D1708) flexural modules (ASTM D790) and Izod
impact strength (ASTM D256 Method A) .
EXAMPLE 1
This example illustrates the preparation of a copolyester from
polyethylene terephthalate by modification with 30 mole %
1,4-cyclohexanedimethanol.
A mixture of 96.0 g (0.50 mole) of scrap polyethylene terephthalate
(I.V. 0.70) and 31.9 g (0.155 mole) 70%
1,4-cyclohexanedimethanol/methanol solution is placed in a 500-ml
flask equipped with a stirrer, a short distillation column and
inlet for nitrogen. The flask is lowered into a metal bath
maintained at 110.degree. C. The mixture is heated under a nitrogen
atmosphere with stirring to a temperature of 275.degree. C. A very
low melt viscosity product is obtained within 5 min. A vacuum of
0.3 millimeter of mercury is then applied over a period of 10 min.
After stirring is continued under 0.3 millimeter of mercury at
275.degree. C. for 44 min., a high-melt viscosity, very light gray
polymer is obtained. The polymer has an inherent viscosity of 0.67
and a glass transition temperature of 77.degree. C. Gas
chromatographic analysis of the hydrolyzed polymer shows that the
polymer contains 29.8% 1,4-cyclohexanedimethanol. Injection-molded
bars have the following properties: tensile strength 6700 psi,
elongation 150%, flexural modulus 2.7.times.10.sup.5 psi and
notched Izod impact strength 1.0 ft-lb/in. of notch. These
properties are very similar to those obtained from the same
copolymer prepared from dimethyl terephthalate, ethylene glycol,
and 1,4-cyclohexanedimethanol.
EXAMPLE 2
This example illustrates the preparation of a copolymer from
poly(ethylene terephthalate) and 5 mole %
1,4-cyclohexanedimethanol.
A copolymer is prepared with 0.5 mole of scrap polyethylene
terephthalate (I.V. 0.32) and 0.025 mole (5 mole %) of
1,4-cyclohexanedimethanol by the procedure of Example 1. A clear,
very light gray polymer is obtained. The polymer has an inherent
viscosity of 0.53, glass transition temperature of 75.degree. C.
and crystalline melting point of 239.degree. C. Gas chromatographic
analyses of the hydrolyzed polymer shows that the polymer contains
5.5% 1,4-cyclohexanedimethanol.
EXAMPLE 3
This example illustrates the preparation of a copolymer from
poly(ethylene terephthalate) and 90 mole %
1,4-cyclohexanedimethanol.
A copolymer is prepared with 0.5 mole of polyethylene terephthalate
and 0.45 mole (90 mole %) of 1,4-cyclohexanedimethanol by the
procedure of Example 1. A clear, very pale yellow polymer is
obtained. The polymer has an inherent viscosity of 0.66, glass
transition temperature of 86.degree. C. and crystalline melting
point of 255.degree. C. Gas chromatographic analysis of the
hydrolyzed polymer shows that the polymer contains 87.2 mole %
1,4-cyclohexanedimethanol.
EXAMPLE 4
This example illustrates the preparation of copoly(90/10 ethylene
terephthalate/cyclohexylenedimethylene terephthalate) by reacting
poly(ethylene terephthalate) and copoly(70/30 ethylene
terephthalate/cyclohexylenedimethylene terephthalate) with
1,4-cyclohexanedimethanol.
A copolymer is prepared with 96 g (0.50 mole) polyethylene
terephthalate, 21.6 g (0.10 mole) copoly(70/30 ethylene
terephthalate/1,4-cyclohexylenedimethylene terephthalate) and 4.3 g
(0.030 mole) 1,4-cyclohexanedimethanol by the procedure of Example
1. The polymer has an inherent viscosity of 0.52, glass transition
temperature of 72.degree. C. and melting point of 227.degree. C.
Gas chromatographic analysis of the hydrolyzed polymer shows that
the polymer contains 10.1% 1,4-cyclohexanedimethanol.
EXAMPLE 5
This example illustrates the preparation of copoly(62/38
1,4-cyclohexylenedimethylene terephthalate/ethylene terephthalate)
from copoly(70/30 ethylene terephthalate/cyclohexylene
terephthalate) and 1,4-cyclohexanedimethanol.
A copolymer is prepared with 0.50 mole copoly(70/30 ethylene
terephthalate/1,4-cyclohexylenedimethylene terephthalate) and 0.16
mole 1,4-cyclohexanedimethanol by the procedure of Example 1. A
high-melt viscosity, clear, very pale yellow polymer is obtained
having an I.V. of 0.64.
EXAMPLE 6
This example illustrates the preparation of copoly(87/13 ethylene
terephthalate/1,4-cyclohexylenedimethylene terephthalate) by solid
state polymerization.
A copolymer is prepared with 0.50 mole of poly(ethylene
terephthalate) and 0.065 mole (13 mole %) of
1,4-cyclohexanedimethanol by the procedure of Example 1. The
copolymer, obtained with an inherent viscosity of 0.61, is ground
to pass a 20-mesh screen. Solid-state build-up is accomplished by
heating the particles under reduced pressure (0.1 mm Hg) at
23.degree.-200.degree. C. over a period of 2 hr. and at 200.degree.
C. for 12 hr. the polymer has an inherent viscosity of 0.81 and a
crystalline melting point of 219.degree. C.
Unless otherwise specified, all parts, percentages, ratios, etc.,
are by weight.
The invention has been described in detail with particular
reference to preferred embodiments thereof, but it will be
understood that variations and modifications can be effected within
the spirit and scope of the invention.
* * * * *